Intravenous (IV) lines are used to convey medicinal fluids into a patient's cardiovascular system. A typical IV line includes a fluid reservoir coupled to one end of a flexible tubing that is connected in fluid communication with a large vein of a patient. An inline IV pump is often employed to effect and control the flow of the medicinal fluid through the tubing to the patient. Also, at least one occlusion sensor is usually included to detect when the flow of fluid through the IV line is fully or partially interrupted. Partial or complete occlusion of fluid flow is one of the more common problems in the use of an IV line. The patient may unintentionally compress the tubing, e.g., by rolling onto it, and stop the fluid flow, or a blood clot may block the flow of fluid where it enters the cardiovascular system. In addition, an electrical or mechanical failure of an IV pump disposed in the IV line may cause the flow of fluid through the line to be impeded. Problems can also arise if false alarms are triggered by minor pumping irregularities or occasional spikes in the signal produced by the occlusion sensor, since too many false alarms can cause medical personnel to ignore valid alarms.
In the prior art, pressure activated occlusion sensors have been disposed at the proximal and distal ends of a disposable pumping cassette (IV pump) for determining when the flow of fluid through the IV line is impeded. When the measured pressures indicate that the flow of fluid is impeded, an alarm is activated that notifies medical personnel of the condition. Typically, a separate assembly is employed for coupling a pressure occlusion sensor to an IV line, and the occlusion sensor is disposed adjacent to an IV pump. However, the limited space adjacent to ambulatory IV pumps has generally restricted the use of pressure occlusion sensors to non-ambulatory IV pumps.
Prior art pressure occlusion sensors typically must be calibrated by medical personnel each time they are coupled to an IV line, using a time consuming procedure. Also, special training is often necessary for medical personnel to be proficient at calibrating the pressure occlusion sensors. Thus, a clear need has developed for a pressure occlusion sensor that is integrated with the IV pump to conserve space and which is automated to implement the calibration procedure. While accurately detecting any significant hindrance to fluid flow, such an occlusion sensor should minimize false alarms.